MFC dishonest

MFC always gives me the worse service they debited more then R12000.00 from my account which is my whole salary after making an arrangement that i will pay an extra R 3000.00 i am calling them to get the difference refunded and i am being told they will call me back or they see my arrangement that will ask the person that made the arrangement to call me back till today the disgusting MFC never called me back. i want the difference to be refunded